Why You May Not Have Noticed Georgia’s Hottest Year on Record

While the end of 2017 saw wind chills in the single digits across the state, the average temperature for the year across Georgia was 2.4°F above normal. That places 2017 in a tie with 2016 as the warmest year in 120 years of record keeping. As for the contiguous United States, 2017 was the third warmest year on record.

It’s important to understand why 2017 could be the warmest year on record. Despite Georgia seeing few excessively hot days during the year and Atlanta receiving three to four inches of snow in December, records like this aren’t established by extreme or newsworthy weather events; they’re established by consistent above-average temperatures throughout the year. A series of 75-degree days in the middle of April, though above average, would hardly prove newsworthy. Snow in Savannah, however, will send Twitter and Facebook into a frenzy. Since little news coverage is given to relatively normal days or days that are perceived to simply be “nice”, it’s easy to miss the long-term trend.

The cold front and “bomb cyclone” that hit the east coast of the U.S. during the final days of 2017 and beginning of 2018 produced bitterly cold days in Georgia. On New Year’s Day, the average temperature in Atlanta was 23.5°F*. That average temperature was 19.5°F below normal and it received headlines in the Atlanta Journal Constitution and other news outlets. However, on January 10, 2018, the average temperature in Atlanta was 16.1°F above normal. While that deviation from the normal is not as great as the deviation on New Year’s Day, it’s still a considerable weather event. Yet, the temperatures on January 10th received almost no news coverage.

Why? Because a 65°F day in January is simply a very nice day. More importantly, the driving force behind the 16.1°F average temperature deviation on January 10th was the low temperature, not the high temperature. While the high temperature for the day, 65°F, was 13°F above normal, the low temperature of 53°F was 19°F above normal. Understandably, few people noticed that it was excessively warm outside while they were sleeping. Those who did notice probably welcomed the warmer weather after experiencing temperatures in the teens several days prior.

While Atlanta experienced very few, if any, excessively hot days in 2017, the days with above-average temperatures far outpaced the days with below-average temperatures. As the figure above shows, 64 percent of days had above-average high temperatures while only 36 percent of days had below-average high temperatures. A similar breakdown was observed for low temperatures.

The figures below show all the days in 2017 with temperature deviations above and below normal. The year can be divided into thirds with the first and last third seeing the greatest temperature variability. The summer months, however, saw fewer temperature deviations; between day 150 and day 250, no temperature deviated above the average by more than 7°F. While January had many days with temperatures soaring 20 or more degrees Fahrenheit above normal, July had none. Similar 20 degree deviations in July would have produced temperatures over 110°F.

This figure shows the days with high temperatures that deviated from normal. For instance, on January 1, 2017, the high temperature was 51°F while the normal temperature for that date is 52°F. The left-most dot on the chart represents that deviation of -1°F. The average deviation above the normal high temperature was 7.5°F while the average deviation below the normal high temperature was 6.15°F. The orange dots represent the temperature deviations that exceeded those averages. For instance, the first orange dot from the left that is below the x-axis represents the high temperature deviation on January 7, 2017. That day recorded a high temperature 21°F below normal.

Extreme high temperatures in the summer months create more hazardous conditions than equivalent temperature increases in the winter months. The same can be said for extreme low temperatures in the winter months vs. the summer months. Due to our proclivity to reserve headline space for such potentially life-threatening events, it’s understandable that the overall warmth of 2017 could get overlooked.

Between our day-to-day obligations and the media industry’s never-ending battle for consumer’s attention, it can be difficult to place particular weather events in the larger context of time and space. While a certain high-profile politician mocked the idea of climate change days before the east coast “bomb cyclone,” the Eastern National Weather Service Region had just experienced its 4th warmest year on record and the western part of North America (and much of the world) was experiencing well-above average temperatures (see images below).

Temperature Deviations from Normal on Date of Politician’s Comment, 29-Dec-2017

As we progress through 2018 keep an eye on both the high temperature and the low temperature each day. The temperature at night is often overlooked, but it is integral to the computation of average temperatures and has a significant impact on the changing climate. Be aware that though warmer weather in the cooler months may be pleasant and welcomed, average increases in temperature on a scale that may be perceived as trivial to humans can negatively impact the economy and increase the spread of tropical disease among many other things. Drought, fires, floods, and other major weather and climate-related events around the world will impact all of us in one way or another.

Please see our Weather+Climate page for monthly updates on weather and climate indices in Atlanta, Georgia, and the Southeast.